I just got a B&K ST-2020 and thought I would post my review of it here since there isn't much info on this amp.
Price paid: $230,ebay
Been wanting an amp such as this for a long time and did serious shopping and research for 9 months prior to purchase. Note, however, that almost all of this was online and/or archival reviews of vintage products. As well as relying on my auditory memory.
Seriously considered Rotel RB-980BX or similar, Yamaha M-60 or similar, Acurus A150, Sumo Polaris among others.
As it turns out this amp is a very good match for my system, in fact, I cannot imagine any of the other amps I was considering (except maybe the Rotel) to sound as good as the B&K in my system.
It has exactly the sort of interior layout that I wanted: power supply in middle and separate amp boards along each side. And those caps are HUGE; they look like oil filters! When I plugged it into a regular wall outlet for initial testing the lights dimmed when I turned it on. As installed, it is plugged directly into the hospital grade outlet on the audio system's dedicated 20A 10ga circuit using a PS Audio Plasma power cord.
It is quiet, powerful, smooth, satisfying, full, open, and has good soundstaging. The most impressive thing is that it sounds the same at all volume levels: background, normal, cranked--it always sounds the same. Also it is very quiet, there is no hiss or hum even with the volume pegged.
Notice I'm NOT saying it is "warm" or "tube like" or whatever. All I know is it mates very well with my Canadian bookshelf speakers. It has a full sound with plenty of bass authority and never gets shrill.
Of course there are a few cons, but none of these (even all together) are dealbreakers, even if I had known about them ahead of time. It has rather small binding posts that only accept like 16ga wire, which forced me to buy a set of banana plugs in order to hook it up. It gets pretty warm at idle. There is a turnoff click and pop through the speakers, although this is mild. The mains and rca jacks are on opposite sides compared to every other piece of gear I own, requiring cord rerouting around the amp. The power specs for all the older B&K amps are given in DIN instead of FTC RMS, which means that this 150w amp is really more like a 135w. But the 225w dynamic power still stands!
Overall I am extremely happy I bought it.
NAD C542 CD player
Rotel RC-970BX preamp
Energy Conissour C-2 speakers on matching sand filled Target stands
WireWorld Orbit III+, pre to power;
XLO/VDO ER-5, CD to pre;
Monster Standard 4-16 doubled for 10ga effective total
full, open, satisfying sound with good bass, 225w dynamic power, huge caps, sounds the same at all volumes, an excellent match to Canadian bookshelf speakers
smallish binding posts, turnoff click and pop (mild), mains and rca jacks on opposite sides as most other gear, stays pretty warm at idle
I checked with B&K and the 2020 has the newer style output devices so if it blows a full retrofit is not required.
8 ohm power = 150w DIN
8 ohm power = estimated 135w RMS
dynamic headroom = 1.5 dB
8 ohm dynamic power = estimated 225w (or 200w if being super conservative)
current = 36 amps peak to peak
damping factor = 180
input impedance = 24.3 Kohms
TIM = .09%
THD = .09%
slew rate = 14v/microsec
S/N = 95 dB
w,d,h = 17,5.75,15.5
weight = 30 lbsThis post is made possible by the generous support of people like you and our sponsors:
Topic - B&K ST-2020 amplifier review - K-Bob 20:25:23 07/5/07 (4)